<!DOCTYPE html>
<html>
<head>
<link rel="author" href="mailto:sammy.gill@apple.com">
<link rel="help" href="https://drafts.csswg.org/css-box-4/#margin-trim-flex">
<meta name="assert" content="Flex items react to change in their flexbox's margin-trim value">
<style>
flexbox {
    display: flex;
    width: min-content;
    flex-wrap: wrap;
    border: 1px solid black;
}
item {
    display: block;
    background-color: green;
    width: 50px;
    height: 50px;
}
.margin {
    margin-block: 10px;
}
</style>
</head>
<body>
    <flexbox>
        <item class="margin"></item>
    </flexbox>
    <flexbox>
        <item></item>
    </flexbox>
</body>
</html>
